1. Field of the Invention
The invention disclosed herein relates to a metal hydride actuation device specifically designed to be actuated by an ambient fire and/or explosion.
2. Description of the Prior Art
The closest known invention relating hereto is the metal hydride actuation device disclosed and claimed by my copending United States patent application bearing Ser. No. 114,522, filed Jan. 23, 1980 now U.S. Pat. No. 4,282,931. The contents of that disclosure are specifically referred to as prior art herein. The essential difference between that invention and the invention disclosed herein relate to the fact that this invention was specifically designed and constructed to be electronic free in operation and the heat source to activate its operation was the very same fire and/or explosion which is to be suppressed. This is accomplished by using one or more spot sensors and a system completely void of electrical or electronic devices of any kind.
Fire protection systems may be actuated to trigger fire suppressant devices by a variety of methods. Much of this prior art is disclosed in my incorporated prior application. Perhaps the closest in overall operation is a SCAD system manufactured by the Ansul Company (Marinette, Wisconsin 54143). In that system, a meltable plastic tube is strung around high fire probability areas. For example, a vehicle useable in a mine could have the tubing placed around its engine and hydraulic systems. This tubing is internally pressurized with nitrogen (N.sub.2) gas to about 80 psig and has one end connected to a centralized actuator which contains a piston, a biasing spring in the piston, a puncture pin, and a high pressure N.sub.2 cartridge with a diaphragm. The other end of the meltable tubing is connected to a pressure making device. The nitrogen gas acts to normally hold the piston in a compressed state against the action of the biasing spring. When a fire occurs near the tubing, it melts to release its enclosed nitrogen gas. The biasing spring then moves the piston which in turn causes the other puncture pin to shear a diaphragm of the high pressure N.sub.2 cartridge. This released N.sub.2 gas is then directed through hose lines to a tank of dry powder fire suppressant material. The mixture is a "fluidized" dry powder which travels through a system of hoses and nozzles to the fire. The problem with this system is twofold. There is the possibility that the pressurized plastic tubing may leak and this same tubing is susceptable to damage or breakage due to chemicals and the harsh environment it is used in. It also requires people and vehicle maintenance for its operation.
U.S. Pat. No. 4,175,667 to P. M. Poeschl et al, assigned to the aforesaid Ansul Company, relates to the same or a very similar system and discloses a double ended piston assembly with a frangible disc that is held in a cocked position under the influence of a pressurized sensor gas. When the pressure is lost, the frangible disc is fractured by a puncture element to thereby operate a responsive device such as a warning device, fire suppression system, and the like.
The essential differences between the present invention and the known prior art, including my copending patent application resides in its intrinsic simplicity, i.e., it is electronics free and actuated by the same fire it detects and seeks to suppress. These two features when viewed along with those known advantages of metal hydride have resulted in a virtually maintenance free inexpensive fire suppression system which is safe, simple, and rugged in operation and has the ability to automatically recock itself. It thus is ideally suited for use on mining machinery and other pieces of operator equipment used in dangerous explosion prone environments where automatic actuation of the fire or explosion suppressant is essential.